Technical Abstract:
Western juniper woodlands are rapidly replacing lower elevation (< 2100 m) quaking aspen stands throughout the northern Great Basin. Aspen restoration is important because these communities provide important habitat for wildlife species and contain a high diversity of understory shrubs and herbaceous species. We evaluated several juniper removal treatments to restore aspen woodlands. Treatments included, selective cutting to increase surface fuels followed by fall or early spring burning, and prescribed fire alone. Selective cutting involved cutting 30 to 75% of mature juniper trees. We tested the effectiveness of treatments at removing juniper from seedlings to mature trees, aspen regeneration, and evaluated recovery of shrub and herbaceous understories. Prescribed fires applied in the fall were the most successful at eliminating all remaining juniper trees and seedlings and stimulating aspen suckering. However, fall fires result in severe reductions in herbaceous cover and may increase exotic weedy species. Spring burning produced less severe fires which were not as effective at removing remaining mature juniper trees or seedlings. In spring treatments, enough junipers remained to re-dominate aspen stands within 80 years. Aspen suckering was about 40% lower in spring burned treatments compared to fall burned treatments. Spring burning had little impact to the herbaceous understory which recovered rapidly and was dominated by perennial grasses. If management objectives are to eliminate invasive western juniper with minimal cutting and stimulate greater aspen suckering, fall burning appears to be the most useful method to employ. If the objective is to rapidly increase perennial herbaceous cover and moderately increase aspen suckering, spring burning is recommended. With spring burning follow-up management will be necessary to remove juniper missed in initial treatments.